I think people have a tendency to get bored with scenes that aren't fast paced, and so they might drop off or stop reading. Obviously, it's your story, so write it how feels best to you, but there are a few chapters toward the beginning of my story "Damsel in the Red Dress" that were just reaching the point of being too much for my editor because the MC had spent so much time alone, but when she then continues toward the part of the story where she interacts more with other people, those chapters seem to get more engagement.
All in all, it still depends on how you want to write your story, but if you're going to make it go slower and take longer, you have to do something to keep them engaged in the plot (namely, making sure that what IS taking place is captivating)